Apparatus for filling a pressure vessel

ABSTRACT

A filling fixture has a flanged base having a cavity and a cover having a bore. The base and cover are urged together by a hinged split ring to form a fluid tight enclosure receiving a gas storage vessel. A rotatable shaft is mounted in the cover to engage and tighten a cap on the vessel.

I United States Patent [151 3,673,762 Bock et al. 1 July 4, 1972 PRESSURE VESSEL UNITED STATES PATENTS [72] Inventors: Herbert G. Bock, Farmington; Walter J. v

1,790,787 2/1931 Badger ..53/83 Smell 2,435,747 2/1948 Larson ..53/86 x [73] Assignee: Chandler Evans Inc., West Hartford,

C Primary ExaminerTravis S. McGehee Attorney--Radford W. Luther [22] Filed: April 23, 1971 211 Appl. No.: 136,860 [571 ABSTRACT A filling fixture has a flanged base having a cavity and a cover Related U'S'Apphcamm Data having a bore. The base and cover are urged together by a [62] Division 5 356,226, April 29, 1969 pat hinged split ring to form a fluid tight enclosure receiving a gas 3 577 6-96 4 storage vessel. A rotatable shaft 18 mounted in the cover to engage and tighten a cap on the vessel [52] US. Cl ..53/86 5 Chin's, 3 Drawing Figures [51] ..B65b 31/02 [58] Field of Search ..53/82, 83, 86, 97, 99,100, 53/101,102, I09

E ./,Z d i 6/73 I 9 F/L L SOURCE //l 2 9? v/vr a j v/Ims' A 82 70 J3 I 34 1 A? i7 0 1 5' I l J 1 65 7 i L 4 4fl73 22 l l APPARATUS FOR FILLING A PRESSURE VESSEL CROSS-REFERENCES TO RELATED APPLICATIONS This is a division of application Ser. No. 856,226, filed Apr. 29, 1969, and now US. Pat. No. 3,577,696.

BACKGROUND OF THE INVENTION This invention generally relates to apparatus for filling pressure vessel to extremely high pressures.

The filling of a pressure vessel, having a threaded cap, to an extremely high pressure presents some unique problems. For example, the fixture employed to perform the filling operation must remain fluidtight throughout the filling operation if a high pressure is to be maintained therein. This requires that the means employed to tighten the cap must not impair the integrity of the enclosure, particularly during the tightening operation. Also, the vessel must be restrained against rotation within the enclosure in such a manner as to not damage the vessel wall.

SUMMARY OF THE INVENTION The invention provides a filling fixture having a base and a cover which define a fluid tight enclosure. A rotatable shaft with a flange thereon is mounted in the cover, and a low friction thrust washer is interposed between the flange and the cover to retain the pressure within the enclosure and minimize the friction between the shaft and the cover engendered by the pressure acting on the exposed surface of the flange. In order to properly position the vessel and prevent its rotation within the enclosure, a contoured support sleeve is positioned in the base to prevent the lower portion of the vessel from bottoming therein and a threaded loading collar, threadably received by the base, embraces the upper portion of the vessel. Both the base and the cover are provided with flanges which are held together by a split ring.

The invention provides a simple, safe and effective means for filling a pressure vessel to an extremely high pressure.

It is a primary object of the invention to provide an apparatus capable of filling a pressure vessel to an extremely high pressure.

Another object is to provide an apparatus for filling a pressure vessel having a threaded cap.

Further objects will be apparent to those versed in the art after examination of the specification and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partial side elevation view of an assembled pressure vessel and cap adapted to be filled by an apparatus according to the present invention.

FIG. 2 is a side elevation view of a pressure vessel filling apparatus according to the instant invention.

FIG. 3 is a side elevation view of the pressure vessel of FIG. 1 threadably engaged with a fluid distribution system.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, a pressure vessel has an externally threaded hollow neck section 12 with a first annular beveled sealing surface 14 and at least one longitudinal local recess 16 disposed on the periphery of said neck section 12. A diaphragm, shown generally at 18, has a cylindrical body 20 with one closed end 22 and an open end having an outwardly projecting terminal flange 24 thereon, said flange 24 defining a second annular beveled sealing surface 26 having a bevel angle 28, surface 26 being substantially the mate to sealing surface 14. The bevel angle 28 of surfaces 14 and 26 is preferably 37 with respect to the vessel longitudinal axis. A metal-to-metal seal is preferred to form a reliable seal under adverse environmentally storage conditions of high stress, humidity, temperature, fungus, dirt, shock and vibration. If a large hardness differential exists between surfaces 26 and 14, an interposed sealing element 30 is not required. However, in the preferred embodiment, where surfaces 26 and 14 are of similarly hard steel, a frustoconical sealing element 30, preferably of tin plated copper which will readily flow under high pressure to fill any minor imperfections in sealing surfaces 26 and 14, is inserted between said sealing surfaces. A diaphragm retaining sleeve, shown generally at 32, has internal threads 34 which engage external threads 33 on neck sec tion 12. Inwardly projecting flange 36, integral with sleeve 32, urges diaphragm terminal flange 24 towards neck section 12 as the engagement between sleeve 32 and neck 12 is increased, thus loading surfaces 14 and 26 against each other or against sealing element 30 if an interposed sealing element is utilized. A slight clearance provided between flange 36 of sleeve 32 and cylindrical body 20 causes sealing surfaces 14 and 26 to mate properly despite minor misalignment of the sealing surfaces with the respective threaded members. Sleeve 32 and diaphragm 18 form a cap somewhat analogous to a conventional threaded bottle cap. Once the desired axial sealing force has been attained as indicated by measurement of torque required to advance the engagement of sleeve 32, an annular lip 38 integral with sleeve 32 is inelastically deformed into recess 16 to fix the relative positions of said vessel 10, diaphragm 18, and sleeve 32 so as to preserve and maintain the integrity of the seal.

Sleeve 32 has external threads 40 thereon which, as shown in detail in FIGS. 2 and 3, are useful both for filling the vessel, and for achieving seal installation of the vessel in a pressure distribution system having therein ram means to puncture closed end 22 of diaphragm 18. A portion of the cylindrical body 20 of diaphragm 18 is elongated and carefully finished to sealingly mate with an O-ring seal 102 housed in said pressure distribution system shown in FIG. 3.

Referring to FIG. 2, a fill fixture, shown generally at 50, comprises a flanged base 52 and a flanged cover 54 held together by a hinged split ring 56 adapted to be closed by a handle (not shown) having a camming action whereby a large lever ratio is applied to axially urge together flanges 55 and 53 of base 52 and cover 54 respectively. Bore 58 in base 52 is adapted to receive vessel 10 loosely therein, support being given to said vessel by a contoured support sleeve 60 positioned in the base of bore 58 such that the end of vessel 10 will not bottom in bore 58. A larger threaded bore 62 in base 52 is adapted to threadably receive a cylindrical loading collar 64 having an inwardly extending flange 65 and conically tapered interior surface 66. Flange 65 bears against a contoured thrust ring 68 which loads vessel 10 against support sleeve 60 and tapered centering ring 70 through conical surface 66. Loading collar 64 is torqued to a value in excess of the torque to be applied later to the vessel cap so that when the latter torque is applied, the vessel will not turn within the fixture. A smooth bore 72, still larger than threaded bore 62 is adapted to sealingly receive an O-ring seal 71 positioned in cylindrical extension member 74 integrally connected to cover 54. It is to be noted that before cover 54 is secured in place, a split nut structure 76, having internal threads 78, is affixed to vessel sleeve 32 such that threads 78 engage external threads 40 on sleeve 32 and such that an internal shoulder 80 on nut 76 bears against flange 36 on sleeve 32. A tapered ring 82 is driven onto split nut 76 with care being taken not to disturb a spring clip 84 placed on the elongated body 20 of diaphragm 18 to grasp said diaphragm and bear against flange 36 of sleeve 32. Clip 84 prevents pressure in the fill fixture from forcing diaphragm 18 into fluid tight engagement with sealing element 30 (shown in FIG. 1) while the cap is slightly backed off to permit gas to enter vessel 10. Nut 76 has therein a rectangular slot 68 adapted to receive driver bit 86 integral with shaft 88 mounted for rotation in bushing 90 in cover 54 and sealingly engaged by O-ring seal 91 in said cover. Shaft 88 has a flange 92 thereon, and a low friction thrust washer 94 is interposed between said flange and said cover to minimize the torsional friction component caused by the gas force tending to blow shaft 88 out of the cover.

With cover 54 sealingly engaging and locked to base 52, gas is supplied for a few seconds to bore 116 via passageway l 10 and gas fill source 112 while a fixture vent valve 114, well known in the art, is held open to purge the fixture of air. When the purging operation is complete, the vent valve 114 is shut and the fixture brought to a pressure somewhat below the desired charge pressure whereupon the temperature within the fixture is recorded and the fixture is pressure filled to the final fill based upon a pressure calculated on the basis of the pressure desired when the fixture has cooled to room temperature. The final charging flow is permitted to fill the fixture and torque is applied to shaft 88 to rotate split nut 76, thereby causing sleeve 32 to rotate therewith and, as shown in FIG. 1, drive diaphragm 18 against sealing element 30 and neck 12 until the desired torque has been provided for optimum sealing. Thereafter, the fixture is vented and the cover removed. Tapered ring 82 is removed and the split nut 76 taken ofi. Loading collar 64 is unthreaded from base 52, items 68 and 70 are removed, and the vessel is removed and weighed carefully to ascertain that the weight increase from a previously recorded empty weight indicates the desired weight of gas. A mass spectrometer is utilized to ensure that the leakage rate is consonant with the specified storage duration; if the leakage rate is satisfactory, lip 38 is crimped into recess 16 to lock the cap in place, as shown in FIG. 1.

Referring to FIG. 3, vessel 10 by means of external threads 40 threadably engages a distribution manifold 100 with O-ring seal 102 engaging elongated body 20 on diaphragm 18. When an electrical command signal is delivered to an explosively actuated cutter valve 104, a ram 106 therein punctures end 22 of diaphragm 18 permitting vessel 10 to supply pressurized gas to passageways within manifold 100 leading to various fin actuating mechanisms.

By way of illustration, a pressure vessel construction, adapted to be filled by an apparatus according to the invention, is shown that limits leakage such than an initial nominal charge of ten cubic inches of Grade A helium at 6,800 psi will be at no less than 6,680 psi after a -year storage period. The material used for sleeve 32, diaphragm 18 and neck section 12, shown in FIG. 1, is AMS 6370 having a nominal C Scale Rockwell hardness of 29. The mated frustoconical sealing area between surfaces 14 and 26, shown in FIG. 1, has an aptwo longitudinal diametrically opposed grooves 16 are approximately 0.l00 inch wide and 0.030 inch deep. Approximately grams of helium are added and leakage must not exceed 9.2 X 10' atms cc/sec. as determined by mass spectrometer analysis.

It will be apparent to those skilled in the art that various changes and modifications may be made in the construction proximate ID. of 0.297 inch, an CD. of 0.435 inch, and a and arrangements of the various elements; accordingly, the description and drawings have been set out to illustrate rather than limit the inventive concept.

What we claim is:

1. A filling fixture comprising:

a base having a cavity therein defined by a lower bore, an intermediate bore larger than the lower bore, and an upper bore larger than the intennediate bore, the cavity serving to receive a pressure vessel;

a cover having a bore therein; 7

a peripheral flange integral with the base;

a peripheral flange integral with the cover for mating engagement with the flange on the base such that the bore in the cover communicates with the cavity, the flanges adapted to be urged together to form a fluid tight enclosure surrounding the vessel; a rotatable shaft mounted in the cover for applying a torque to the vessel to seal the vessel;

passageway means to direct a high pressure gas into the enclosure; and

means to vent the enclosure.

2. A filling fixture, as defined in claim 1, further including:

a flange on the shaft, the flange being located within the bore in the cover; and

a low friction thrust washer interposed between the flange and the cover to minimize the torsional friction component caused by the gas force tending to blow the shaft out of the cover.

3. A filling fixture, as defined in claim 1, further including:

a contoured support sleeve positioned in the base of the lower bore for preventing the vessel from bottoming therein; and

a threaded loading collar threadably received by the intermediate bore for preventing turning of the vessel within the fixture. v

4. A filling fixture, as defined in claim 1, further including:

a cylindrical extension member integrally connected to the cover and adapted to be slidingly received in the upper bore; and

an O-ring seal positioned in the member.

5. A filling fixture, as defined in claim 1, further including:

means to urge the flanges together. 

1. A filling fixture comprising: a base having a cavity therein defined by a lower bore, an intermediate bore larger than the lower bore, and an upper bore larger than the intermediate bore, the cavity serving to receive a pressure vessel; a cover having a bore therein; a peripheral flange integral with the base; a peripheral flange integral with the cover for mating engagement with the flange on the base such that the bore in the cover communicates with the cavity, the flanges adapted to be urged together to form a fluid tight enclosure surrounding the vessel; a rotatable shaft mounted in the cover for applying a torque to the vessel to seal the vessel; passageway means to direct a high pressure gas into the enclosure; and means to vent the enclosure.
 2. A filling fixture, as defined in claim 1, further including: a flange on the shaft, the flange being located within the bore in the cover; and a low friction thrust washer interposed between the flange and the cover to minimize the torsional friction component caused by the gas force tending to blow the shaft out of the cover.
 3. A filling fixture, as defined in claim 1, further including: a contoured support sleeve positioned in the base of the lower bore for preventing the vessel from bottoming therein; and a threaded loading collar threadably received by the intermediate bore for preventing turning of the vessel within the fixture.
 4. A filling fixture, as defined in claim 1, further including: a cylindrical extension member integrally connected to the cover and adapted to be slidingly received in the upper bore; and an O-ring seal positioned in the member.
 5. A filling fixture, as defined in claim 1, further including: means to urge the flanges together. 